caa a22 4500 397551096 CHVBK 20180308164750.0 cr unu---uuuuu 161202e199604 xx s 000 0 eng 10.1006/jmsc.1996.0063 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0063 Adaptive behaviour of herring schools in the Norwegian Sea as revealed by high-resolution sonar [Elektronische Daten] [Tony J. Pitcher, Ole Arve Misund, Anders Fernö, Bjørn Totland, Vebjørn Melle] Fourteen herring schools swimming and actively feeding in 15-40 m depth in the Norwegian Sea were followed for about 1 h each in May 1994 using SIMRAD SA950 sidescan sonar: most of the schools were not recorded by a conventional echo-sounder because of vessel avoidance. Acoustic target identities were validated using trawl samples and stomach analysis. The dynamics of changes in school structure were analysed in relation to stimuli impinging on the schools. School structure changed in response to approaches by other herring schools, likely predators, and the research vessel. Over 230 behavioural events, at approximately 5 min intervals, reveal a surprisingly dynamic regime of approaching, joining, and splitting that could facilitate rapid adaptive adjustment of herring school size to prevailing conditions. Moreover, our interpretation of the visualization of the schools by sonar suggests adaptive responses to different kinds of predatory attacks. Individual cod and haddock predators intimately accompanied the herring schools, their attacks causing frequent modifications to, but not dispersal of, school structure, so that most herring were able to continue feeding while retaining the risk-dilution advantages of schooling. On the other hand, rapid approach by fast-moving schooling predators such as saithe, or by the research vessel, caused the herring to dive steeply. Consequent loss of feeding and reassembly was evidently a cost of evading these more dangerous predators. © 1996 International Council for the Exploration of the Sea Regular Articles nationallicence adaptive behaviour nationallicence herring nationallicence predators nationallicence schooling nationallicence sidescan sonar nationallicence vessel avoidance nationallicence Pitcher Tony J. Fisheries Centre, 2204 Main Mall, University of British Columbia Vancouver, Canada, V6T 1ZA aut Misund Ole Arve Institute of Marine Research Bergen, Norway aut Fernö Anders Department of Fisheries and Marine Biology, University of Bergen Bergen, Norway aut Totland Bjørn Institute of Marine Research Bergen, Norway aut Melle Vebjørn Institute of Marine Research Bergen, Norway aut ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 449-452 1054-3139 53:2<449 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0063 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0063 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pitcher Tony J. Fisheries Centre, 2204 Main Mall, University of British Columbia Vancouver, Canada, V6T 1ZA aut NATIONALLICENCE 700 1- Misund Ole Arve Institute of Marine Research Bergen, Norway aut NATIONALLICENCE 700 1- Fernö Anders Department of Fisheries and Marine Biology, University of Bergen Bergen, Norway aut NATIONALLICENCE 700 1- Totland Bjørn Institute of Marine Research Bergen, Norway aut NATIONALLICENCE 700 1- Melle Vebjørn Institute of Marine Research Bergen, Norway aut NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 449-452 1054-3139 53:2<449 1996 53 icesjms Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford